The present invention relates to an encoding and decoding system of a motion image containing an arbitrary object.
Recently, international standards for transmitting a motion image at a very low bit rate have been progressively advancing in order to be applied to a video phone or a video conference system. To transmit a motion image at a very low rate, an object-oriented encoding technique for partitioning a meaningful object in the motion image and transmitting the partitioned object is being widely studied. The object-oriented encoding technique is recognized as an essential technique in order to transmit a motion image at a very low bit rate. In the object-oriented encoding of a motion image, a motion prediction technique for removing temporal correlation with respect to an object is required and a more accurate motion prediction technique is also needed for enhancing encoding efficiency.
It is an object of the present invention to provide an encoding apparatus for a motion image containing an arbitrary object in which the arbitrary object extracted from an image is represented as meshes, and control points of the meshes are used for motion predictive encoding of the image.
Another object of the present invention is to provide a decoding apparatus for decoding data encoded in the above encoding apparatus.
To accomplish the above object of the present invention, there is provided a motion image encoding apparatus for encoding a current image containing an object, the motion image encoding apparatus comprising: an object extraction unit for extracting the object contained in the current image from received current image data and outputting object contour data indicating a contour of the extracted object; a predictive encoding unit for performing a predictive encoding operation using the current image data, prestored data of a reference image, and control points of meshes which divide one of the current image and the reference image, and generating motion information involved with the control points, differential data between the current image and the reference image, and predictive image data; an object difference generator for selecting differential data in an object region among the differential data supplied from the predictive encoding unit to encode the selected differential data based on the object contour data output from the object extraction unit, and generating the selected differential data and the encoded differential data; and an addition unit for receiving and adding the predictive image data output from the predictive encoding unit and the differential data selected in the object difference generator, and updating the reference image data prestored in the predictive encoding unit using the image data obtained by the addition result.
To accomplish the other object of the present is invention, there is also provided a motion image decoding apparatus for decoding the output of a motion image encoding apparatus, the motion image decoding apparatus comprising: an object contour restoring unit for decoding received encoded object contour data and restoring object contour data indicating a contour of an object contained in a current image; a differential data decoding unit for decoding the received encoded differential data and outputting differential data; a motion compensation decoding unit for performing a motion compensation operation using the object contour data, prestored reference image data, control points of meshes which divide one of an object contour and a reference image, and motion information involved with the control points; and an addition unit for adding the predictive image data selected by the object contour data and the differential data, and updating the reference image data prestored in the motion compensation decoding unit using the image data obtained by the addition result.